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Coalbed methane is primarily stored as free gas in conventional porous rock formations, similar to sandstone reservoirs.
Answer: False
Coalbed methane is stored within the solid matrix of the coal through adsorption, existing in a near-liquid state lining internal pores, rather than as free gas in conventional porous rock.
The designation 'sweet gas' for coalbed methane signifies the presence of hydrogen sulfide, a compound considered desirable in natural gas.
Answer: False
Coalbed methane is referred to as 'sweet gas' because it lacks hydrogen sulfide, which is an undesirable compound that causes a sour smell and can be corrosive.
Methane is stored in coal in a near-liquid state, lining the internal pores of the coal matrix.
Answer: True
Methane is stored within the solid matrix of the coal through adsorption, existing in a near-liquid state, lining the internal pores of the coal.
Which of the following is NOT an alternative name for coalbed methane?
Answer: Coal mine gas
Alternative names for coalbed methane include CBM, coalbed gas, and coal seam gas (CSG). 'Coal mine gas' is not listed as an alternative name for the resource itself, though methane is a gas found in coal mines.
Why is coalbed methane referred to as 'sweet gas'?
Answer: It lacks hydrogen sulfide, which causes a sour smell.
Coalbed methane is termed 'sweet gas' because it does not contain hydrogen sulfide, a compound known for its sour odor and corrosive properties.
How is methane primarily stored within the coal matrix in coalbed methane reservoirs?
Answer: Through adsorption in a near-liquid state lining internal pores.
Methane in coalbed methane reservoirs is primarily stored through adsorption within the solid coal matrix, existing in a near-liquid state that lines the internal pores.
What is a typical chemical characteristic of coalbed methane compared to conventional natural gas?
Answer: It contains very few heavier hydrocarbons like propane or butane.
Coalbed methane typically contains minimal quantities of heavier hydrocarbons such as propane or butane, and it does not contain natural-gas condensate, distinguishing it from many conventional natural gas compositions.
In coal seams with regular groundwater recharge, how is methane often generated?
Answer: By microbial communities living in situ.
In coal seams characterized by regular groundwater recharge, methane is frequently generated by in-situ microbial communities.
Coalbed methane reservoirs are characterized as dual-porosity systems, where cleats facilitate gas flow and the coal matrix serves as the primary gas storage medium.
Answer: True
In dual-porosity CBM reservoirs, cleats (natural fractures) are responsible for gas flow, while the coal matrix itself stores the gas through adsorption.
The overall porosity of a coalbed methane reservoir typically ranges from 0.1% to 1%, while cleat porosity is much higher.
Answer: False
The overall porosity of a coalbed methane reservoir typically ranges from 10% to 20%, whereas cleat porosity is much lower, estimated between 0.1% and 1%.
Adsorption capacity in coal is measured in standard cubic feet (SCF) of gas per unit mass of coal and is primarily influenced by the depth of the coal seam.
Answer: False
Adsorption capacity in coal is primarily influenced by the rank and quality of the coal, not its depth.
During coalbed methane production, water is initially pumped out to increase reservoir pressure, which aids in gas desorption.
Answer: False
During CBM production, water is initially pumped out to *reduce* reservoir pressure, which in turn enhances gas desorption from the coal matrix.
Fracture permeability in coalbed methane reservoirs typically decreases with gas depletion, similar to conventional reservoirs.
Answer: False
Unlike conventional reservoirs, fracture permeability in coalbed methane reservoirs tends to *increase* with gas depletion as the coal matrix shrinks, widening existing fractures.
The 'negative decline' characteristic of CBM wells implies that gas production rates initially decrease before stabilizing.
Answer: False
The 'negative decline' characteristic of CBM wells means that gas production rates initially *increase* as water is pumped off, allowing gas to desorb and flow more freely, before eventually declining.
The Langmuir isotherm describes the relationship between gas content and reservoir pressure, defined by Langmuir volume and Langmuir pressure.
Answer: True
The Langmuir isotherm is a curve that models the methane desorption process, illustrating the relationship between gas content and reservoir pressure, and is defined by the Langmuir volume and Langmuir pressure.
A vitrinite reflectance between 0.8% and 1.5% is generally associated with lower coalbed productivity.
Answer: False
A vitrinite reflectance between 0.8% and 1.5% is associated with *higher* coalbed productivity, not lower.
For coalbed gas to be considered 'pipeline quality,' its methane composition should ideally be less than 92%.
Answer: False
For coalbed gas to achieve 'pipeline quality,' its methane composition should ideally be *greater than* 92%.
Coalbed methane wells typically produce gas at higher rates than conventional reservoirs, often exceeding 500,000 cubic feet per day.
Answer: False
Coalbed methane wells generally produce gas at *lower* rates than conventional reservoirs, typically peaking at around 300,000 cubic feet per day.
What are the two types of porosity in a coalbed methane dual-porosity reservoir?
Answer: Cleat porosity for gas flow and coal matrix porosity for gas storage.
In a dual-porosity CBM reservoir, cleat porosity facilitates gas flow, while the coal matrix porosity is responsible for gas storage.
What is the typical range for cleat porosity in a coalbed methane reservoir?
Answer: 0.1% to 1%
Cleat porosity in a coalbed methane reservoir is typically much lower than overall porosity, estimated to be in the range of 0.1% to 1%.
What is the primary factor influencing the adsorption capacity of coal?
Answer: The rank and quality of the coal.
The adsorption capacity of coal, defined as the volume of gas adsorbed per unit mass, is primarily influenced by the rank and quality of the coal.
How does the initial pumping of water from a coalbed methane reservoir contribute to gas production?
Answer: It reduces pressure, enhancing gas desorption from the coal matrix.
The initial pumping of water from a CBM reservoir reduces the pressure within the reservoir, which in turn enhances the desorption of gas from the coal matrix, allowing methane to be released and flow.
What is the typical range for fracture permeability in most US coal seams?
Answer: 0.1 to 50 milliDarcys
For most US coal seams, fracture permeability, which is the main channel for gas flow, typically falls within the range of 0.1 to 50 milliDarcys.
How does fracture permeability in coalbed methane reservoirs typically behave as gas depletion occurs?
Answer: It tends to increase as the coal matrix shrinks.
Unlike conventional reservoirs, fracture permeability in coalbed methane reservoirs tends to increase with gas depletion because the coal matrix shrinks as methane is released, opening up existing fractures.
What does the 'negative decline' characteristic in coalbed methane well production profiles signify?
Answer: Gas production rates initially increase before declining.
The 'negative decline' characteristic indicates that gas production rates in CBM wells initially increase as water is pumped off and gas desorbs, before eventually entering a decline phase.
Which of the following is a key criterion for high coalbed productivity in a CBM source?
Answer: Vitrinite reflectance between 0.8% and 1.5%.
A vitrinite reflectance between 0.8% and 1.5% is a key criterion associated with higher coalbed productivity in a CBM source, alongside high cleat density and vitrinite composition.
What is the minimum methane composition generally required for coalbed gas to achieve 'pipeline quality'?
Answer: Greater than 92%
For coalbed gas to be considered 'pipeline quality' and commercially marketable, its methane composition should ideally be greater than 92%.
What is the typical peak production rate for coalbed methane wells?
Answer: Around 300,000 cubic feet per day.
Coalbed methane wells typically peak at production rates of approximately 300,000 cubic feet per day, which is generally lower than conventional reservoirs.
Methane has a lower global warming potential per unit of mass compared to carbon dioxide over a 20-year period.
Answer: False
Methane is rated as having a significantly *higher* global warming potential per unit of mass than carbon dioxide, specifically 72 times more potent over a 20-year period.
Generating electricity from coalbed methane results in more than double the greenhouse gas effect compared to generating electricity from coal.
Answer: False
Generating electricity from coalbed methane results in *less than half* the greenhouse gas effect compared to generating electricity from coal.
In the United States, methane escaping from coal during mining accounts for seven percent of total methane emissions.
Answer: True
Methane escaping from coal during mining operations in the United States accounts for seven percent of the nation's total methane emissions.
Produced water from CBM extraction is consistently of high quality across all regions, making it suitable for direct release into streams without treatment.
Answer: False
The quality of produced water from CBM extraction varies significantly by region and may contain undesirable concentrations of dissolved substances, often requiring treatment before release or beneficial use.
Produced water from coalbed methane wells in the Powder River Basin, US, is widely used for irrigation due to its low sodium adsorption ratio.
Answer: False
While produced water in the Powder River Basin often meets drinking water standards and is used for livestock, its use for irrigation is limited by a relatively *high* sodium adsorption ratio.
The National Water Commission in Australia estimates annual groundwater extraction by the CBM industry to be less than 100,000 million litres.
Answer: False
The National Water Commission in Australia estimates annual groundwater extraction by the CBM industry to be even higher than industry estimates, exceeding 300,000 million litres.
Over a 20-year period, how much more potent is methane as a greenhouse gas compared to carbon dioxide?
Answer: 72 times
Methane is significantly more potent as a greenhouse gas than carbon dioxide, rated at 72 times more potent over a 20-year period.
How do life-cycle greenhouse gas emissions from CBM electricity generation compare to coal electricity generation?
Answer: CBM results in less than half the GHG effect.
Life-cycle analysis indicates that generating electricity from coalbed methane results in less than half the greenhouse gas effect compared to generating electricity from coal.
What percentage of total US methane emissions is attributed to methane escaping from coal during mining?
Answer: Seven percent
Methane escaping from coal during mining operations accounts for seven percent of total methane emissions in the United States.
Which of the following is NOT a typical method for managing 'produced water' from CBM extraction?
Answer: Direct discharge into municipal drinking water supplies.
Direct discharge into municipal drinking water supplies is not a typical method for managing produced water from CBM extraction; rather, it is managed through reinjection, controlled release, irrigation (often after treatment), or evaporation ponds.
What environmental issue led to Eastern Star Gas being fined in the Pilliga Scrub, Australia, in 2012?
Answer: Discharging polluting water with high salt levels into a creek.
In 2012, Eastern Star Gas was fined for discharging polluting water with high salt levels into Bohena Creek in the Pilliga Scrub, Australia, among other related incidents.
What factor limits the use of produced water from CBM wells in the Powder River Basin for irrigation, despite often meeting drinking water standards?
Answer: Its relatively high sodium adsorption ratio.
Despite often meeting federal drinking water standards, produced water from CBM wells in the Powder River Basin has a relatively high sodium adsorption ratio, which limits its suitability for irrigation.
According to the National Water Commission, what is the estimated annual groundwater extraction by the CBM industry in Australia?
Answer: Exceeding 300,000 million litres.
The National Water Commission estimates that the annual groundwater extraction by the CBM industry in Australia exceeds 300,000 million litres, which is higher than the industry's own estimates.
In the late 1970s, the US federal government encouraged coalbed methane production by funding research and implementing federal price controls.
Answer: False
The US federal government encouraged CBM production in the late 1970s by funding research and *exempting* coalbed methane from federal price controls, which had previously kept natural gas prices artificially low.
Commercial extraction of coal seam gas in Australia commenced in 1996 within the Surat Basin.
Answer: False
Commercial extraction of coal seam gas in Australia began in 1996 within the Bowen Basin, not the Surat Basin.
The Energy and Resources Institute (TERI) in India is exploring thermal cracking techniques to enhance methane recovery from coal beds.
Answer: False
The Energy and Resources Institute (TERI) in India is investigating *microbial techniques* to enhance methane recovery from coal beds, not thermal cracking.
The Aspen Skiing Company constructed a 3-megawatt methane-to-electricity plant in Wyoming in 2012.
Answer: False
The Aspen Skiing Company constructed a 3-megawatt methane-to-electricity plant in Somerset, *Colorado*, in 2012, not Wyoming.
As of 2014, coal seam gas from Queensland and New South Wales accounted for approximately ten percent of Australia's total gas production.
Answer: True
As of 2014, coal seam gas from Queensland and New South Wales indeed constituted approximately ten percent of Australia's total gas production.
The main coal basins in Australia containing coal seam gas resources include the Bowen, Surat, and Perth Basins.
Answer: False
The main coal basins in Australia containing coal seam gas resources include the Bowen, Surat, and *Sydney* Basins, with additional potential in South Australia, not the Perth Basin.
British Columbia is estimated to possess approximately 170 trillion cubic feet of coalbed gas, while Alberta has about 90 trillion cubic feet.
Answer: False
British Columbia is estimated to possess approximately 90 trillion cubic feet of coalbed gas, while Alberta had an estimated 170 trillion cubic feet of economically recoverable CBM as of 2013.
In Alberta, Canada, the debate over coalbed methane's classification as renewable or non-renewable has implications for provincial ownership rights.
Answer: True
The debate in Alberta regarding CBM's classification as renewable or non-renewable directly impacts provincial ownership rights, as only non-renewable resources are legally owned by the province.
The United Kingdom's coalbed methane potential is largely untapped, with only about 10% of its estimated gas in place believed to be economically recoverable.
Answer: False
The United Kingdom's coalbed methane potential is largely untapped, with only about *one percent* of its estimated gas in place believed to be economically recoverable.
In 2017, the United States' coalbed methane production reached its peak at 1.97 trillion cubic feet.
Answer: False
The United States' coalbed methane production peaked in *2008* at 1.97 trillion cubic feet; in 2017, it was 1.76 trillion cubic feet.
The Rocky Mountain states, including Colorado, Wyoming, and New Mexico, are the primary producers of coalbed methane in the United States.
Answer: True
The majority of coalbed methane production in the United States originates from the Rocky Mountain states, specifically Colorado, Wyoming, and New Mexico.
Kazakhstan's main coalfields are estimated to hold 85% of the country's total gas reserves in the form of coalbed methane.
Answer: True
Preliminary research suggests that Kazakhstan's main coalfields may hold as much as 900 billion cubic meters of gas, representing 85% of all gas reserves in the country, indicating significant CBM potential.
Great Eastern Energy (GEECL) was the first company to make coalbed methane commercially available in India in 2007.
Answer: True
Great Eastern Energy (GEECL) was indeed the first company to have a field development plan approved and made coalbed methane commercially available in India on July 14, 2007.
Initially, the majority of commercially available coalbed methane in India was used for industrial heating purposes.
Answer: False
Initially, 90% of the commercially available coalbed methane in India was distributed as Compressed Natural Gas (CNG) to fuel vehicles, not primarily for industrial heating.
The Essar Group holds a portfolio of ten coalbed methane blocks in India, with most of them currently operational.
Answer: False
The Essar Group holds a portfolio of *five* coalbed methane blocks in India, and only one of them (Raniganj East) is currently operational.
What historical safety measure was implemented in coal mining to mitigate the risk of methane (firedamp)?
Answer: Drilling boreholes from the surface to vent methane.
Historically, boreholes were drilled from the surface into coal seams to vent methane (firedamp) as a safety measure before mining operations commenced.
Which action did the US federal government take in the late 1970s to stimulate coalbed methane as a natural gas resource?
Answer: Provided a federal tax credit to encourage its production.
In the late 1970s, the US federal government provided a federal tax credit to encourage the production of coalbed methane, alongside funding research and exempting it from price controls.
When did commercial extraction of coal seam gas begin in Australia, and in which basin?
Answer: 1996, Bowen Basin
Commercial extraction of coal seam gas in Australia commenced in 1996 within the Bowen Basin, Queensland.
What innovative technique is TERI in India exploring to enhance methane recovery from coal beds?
Answer: Microbial techniques.
The Energy and Resources Institute (TERI) in India is investigating microbial techniques to enhance methane recovery from coal beds, with successful field trials already reported.
In 2012, the Aspen Skiing Company constructed a methane-to-electricity plant in which US state?
Answer: Colorado
In 2012, the Aspen Skiing Company constructed a 3-megawatt methane-to-electricity plant in Somerset, Colorado.
As of 2014, what percentage of Australia's total gas production was constituted by coal seam gas from Queensland and New South Wales?
Answer: Ten percent
As of 2014, coal seam gas from Queensland and New South Wales accounted for approximately ten percent of Australia's total gas production.
Which of the following is NOT listed as a major coal basin in Australia containing coal seam gas resources?
Answer: Perth Basin
The major coal basins in Australia containing coal seam gas resources are the Bowen, Surat, and Sydney Basins, with additional potential in South Australia; the Perth Basin is not listed among these.
What was the United States' peak coalbed methane production year and volume?
Answer: 2008, 1.97 trillion cubic feet
The United States' peak coalbed methane production occurred in 2008, reaching a volume of 1.97 trillion cubic feet.
Which group of US states are the primary producers of coalbed methane?
Answer: Rocky Mountain states (e.g., Colorado, Wyoming, New Mexico)
The Rocky Mountain states, specifically Colorado, Wyoming, and New Mexico, are the primary producers of coalbed methane in the United States.